Digital Image Processing (DIP) is applied for image denoising, image enhancement, image segmentation and feature extraction by using a computer.
DIP is firstly used in the 1950s, the computer is designed and can be applied to process graphics information to improve the image resolution [1]}.
DIP has been widely used in many fields.
Agricultural and forestry departments can detect pesticides in vegetables, identify the rice varieties,
design various piking robots and monitor the management of diseases and insect pests
 [2]}.
The water conservancy department can prevent the disaster of water in advance through remote sensing image analysis [3]}.
Image segmentation technology, image description method and pattern recognition technology are used to identify and detect fire disaster [4]}.
The traffic controlling department can use DIP to monitor the road condition, recognize license plate number, and violate detection [5]}.
Medical departments can use amounts of DIP technology to automatically classify and segment various diseases [6]}, [7]}, [8]}, [9]}, [10]}.
The professional equipment is necessary for microbial researches to achieve the better precision.
However, the use of DIP can reduce the equipment costs [11]}.
Meanwhile, DIP has been applied in the field of microorganism biovolume measurement widely.
The trend of development is shown in Fig. REF .
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